1. Field of the Invention
This invention relates to an optical connector, and more particularly to an optical connector having waterproof properties.
2. Description of Related Art
Conventionally, there has been proposed an optical connector comprising a shell member, an insulator, ferrules, sealing members, and fiber holding members (see Japanese Laid-Open Patent Publication (Kokai) No. H10-311933, Paragraph Nos. 0016 to 0022 and FIG. 1).
The shell member has a substantially hollow cylindrical shape and has a flange-shaped shell-holding portion formed on an outer peripheral surface thereof. A protrusion is formed on an inner peripheral surface of a front end portion of the shell member, and a groove is formed in an inner peripheral surface of a rear end portion of the shell member along a circumferential direction thereof. A stopper member is removably mounted on the groove.
The insulator has a substantially hollow cylindrical shape, and is inserted into the shell member to be fixed by the protrusion of the shell member and the stopper member. The insulator is formed with a through hole. The through hole extends in a fitting/removing direction of the optical connector with respect to a mating optical connector. A female screw is formed on an inner peripheral surface of a rear end portion of the through hole. An inner diameter of a front end portion of the through hole is smaller than inner diameters of the other portions of the through hole, and the inner diameters of the other portions of the through hole are substantially equal to each other.
The ferrule has a substantially hollow cylindrical shape and holds an optical fiber strand of one end portion of an optical fiber code. The ferrule includes a flange-shaped ferrule-holding portion.
The ferrule is inserted into the through hole of the insulator. A front end portion of the ferrule protrudes from the front portion of the through hole. The ferrule-holding portion of the ferrule is brought into abutment with a stepped surface (stepped surface that is adjacent to a rear of the front end portion of the through hole) in the through hole of the insulator.
The sealing member is formed of an elastic material such that it has a substantially annular shape, and is mounted on a rear end portion of the ferrule. The sealing member prevents water from passing through the through hole.
The fiber-holding member has a substantially hollow cylindrical shape and includes a fiber through hole. The optical fiber code is passed through the fiber through hole. Also, the rear end portion of the ferrule is inserted into a front end portion of the fiber through hole. A male screw that is screwed into the female screw of the insulator is formed on an outer peripheral surface of a rear end portion of the fiber-holding member.
Next, a description will be given of assembly of the conventional optical connector.
As a preparation for the assembly, the optical fiber code is passed through the fiber-holding member and the ferrule having the sealing member mounted thereon is caused to hold the optical fiber strand of the one end portion of the optical fiber code, in advance.
First, the insulator is inserted into the shell member until the insulator is brought into abutment with the protrusion of the shell member.
When the insulator is brought into abutment with the protrusion of the shell member, the stopper member is mounted in the groove of the shell member to fix the insulator to the shell member.
Next, the ferrule having the sealing member mounted thereon is inserted into the through hole of the insulator and is pushed in to the front end portion of the through hole by using e.g. a jig. When the ferrule is pushed in, the front end portion of the ferrule protrudes forward from the through hole.
Finally, the fiber-holding member is inserted into the through hole of the insulator, and the male screw of the fiber-holding member is screwed into the female screw of the insulator, whereby the sealing member is pressed to the ferrule-holding portion of the ferrule with a front end of the fiber-holding member.
When through the above-described process, the assembly of the optical connector is completed.
In the above-described optical connector, when the ferrule having the sealing member mounted thereon is inserted into the through hole of the insulator and is pressed in to the front end portion of the through hole by using e.g. a jig, the sealing member is moved while being rubbed against the inner peripheral surface (especially the female screw portion) of the through hole. Therefore, there is a fear that the sealing member is damaged. As a result, there is a fear that the optical connector cannot be made waterproof.